Question

When unpolarized light incident from air on another medium at an angle of 60°, the reflected light is completely polarized. The refractive index of the medium is:

• A. \( \sqrt{3} \)
• B. \( \frac{\sqrt{3}}{2} \)
• C. \( \sqrt{2} \)
• D. \( \frac{2}{\sqrt{3}} \)

Hint:

The Brewster angle is the angle of incidence at which light is perfectly polarized upon reflection. The refractive index of the medium can be directly found using the tangent of this angle.

Answer 1

The Correct Option is A

Step 1: For the reflected light to be completely polarized, the angle of incidence must be equal to the Brewster angle, \( \theta_B \), which is given by: \[ \tan \theta_B = n \] where \( n \) is the refractive index of the medium. 

Step 2: Given that the angle of incidence is \( 60^\circ \), we can equate this to the Brewster angle: \[ \tan 60^\circ = n \] \[ n = \sqrt{3} \]